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60.3: Elements of a geologic map

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    Given that all these maps of all these different places depict a great variety of different rocks, what do they all have in common? In general, geologic maps consist of several key elements, or components. They include:

    • A base map, usually a topographic map of the region. Topographic maps depict the shape of the land using contour lines of a set elevation.
    • The usual stuff that goes along with a topographic base map, such as a scale, a reference map, latitude and longitude, and magnetic declination (the angle of difference between magnetic north and geographic north).
    • Distinct geologic units, differentiated from one another by some distinction, like different colors or different fill patterns, as well as an abbreviated identifier code. For instance, the Cambrian-aged Weverton Formation might be tan in color, and would be abbreviated C\(_{\text{W}}\).
    • Contacts between different geologic formations. These contacts might be comformable stratigraphic contacts, unconformities, faults, or intrusions.
    • Symbols showing the measured orientation of rock structures, such as bedding, foliation, and faults.
    • Other symbols showing the interpreted structure of the region, such as anticlines, synclines, normal faults, thrust faults, and transform faults.

    This page titled 60.3: Elements of a geologic map is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Callan Bentley, Karen Layou, Russ Kohrs, Shelley Jaye, Matt Affolter, and Brian Ricketts (VIVA, the Virginia Library Consortium) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.